Adaptive response time acceleration

ABSTRACT

This document discusses among other things, methods and apparatus to conserve energy when providing proximity information. An example apparatus can include an energy emitter configured to emit a first pulse of energy, an energy sensor configured to receive reflected energy from the first pulse of energy, a control circuit including a processor, the processor configured to provide first proximity information of the apparatus with respect to an object using the reflected energy. The control circuit can be configured to control the energy emitter, to compare the first proximity information with second proximity information, and to modulate a delay between the first pulse of energy and a subsequent pulse of energy using the comparison.

BACKGROUND

Proximity sensors are used in number of applications, for example, tosense the location of a particular device with respect to the locationof a proximity sensor or to sense the relative proximity of an objectwith respect to a second object. A method of proximity sensing includesemitting energy and sensing reflected energy. The method can be repeatedat a given frequency indefinitely to continuously monitor and provideproximity information. The proximity information can be used to controloperation of a system the proximity sensor is used with.

OVERVIEW

In certain examples, methods and apparatus can conserve energy whenproviding proximity information. An example apparatus can include anenergy source, such as an energy emitter, configured to emit a firstpulse of energy, an energy sensor configured to receive reflected energyfrom the first pulse of energy, and a control circuit including aprocessor, the processor configured to provide first proximityinformation of the apparatus with respect to an object using thereflected energy. The control circuit can be configured to control theenergy source, to compare the first proximity information with secondproximity information, and to modulate a delay between the first pulseof energy and a subsequent pulse of energy using the comparison.

This overview is intended to provide an overview of subject matter ofthe present patent application. It is not intended to provide anexclusive or exhaustive explanation of the invention. The detaileddescription is included to provide further information about the presentpatent application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates generally an example of a proximity sensor.

FIG. 2 illustrates generally an example of a proximity sensor.

FIG. 3 illustrates generally a number of adaptive response timeacceleration curves that can be used to control a proximity sensor.

FIG. 4 illustrates generally an example of a method for efficientlyproviding timely and accurate proximity information.

DETAILED DESCRIPTION

In certain examples, a proximity sensor can be used with an electronicdevice to control various features of the electronic device. Forexample, a proximity sensor can be used with a cell phone to help theusability of the cell phone by dimming the screen of the cell phone whenthe phone is near the user's face or when the cell phone screen is awayfrom an object for an extended period of time. Such automated screendimming can save a significant amount of battery energy. In someexamples, proximity information from the sensor can be used to disablethe cell phone screen when the phone is brought near the user's face,such that touching of the cell phone screen on the user's face does nottrigger unintended keystrokes of the cell phone screen. In an example,the proximity sensor emits a pulse of energy and detects energy from thepulse reflected from an object near the sensor. The energy emission canbe repeated at a fixed or other frequencies to provide on-goingproximity information. The energy of the pulse can include, but is notlimited to, light energy, such as visible or infrared light energy,acoustic energy, such as ultrasonic acoustic energy, or electromagneticenergy, such as radio frequency energy or inductive electromagneticenergy.

The inventors have recognized, among other things, that sensingproximity information at a constant frequency, for example, to disable acell phone touch screen, wastes energy and reduces the useful chargelife of an electronic device that relies on a limited power source, suchas a battery. However, during some operations of a device, high speedproximity sensing can enhance the usability of a device because highspeed proximity sensing can detect changes in the proximity between thedevise and an object. Proximity information, including informationindicating a change-in-proximity information, can be used to furtherenhance the usability of an electronic device. At the same time,however, on-going high speed sensing, such as when a cell phone issitting on a night stand or is being used near the user's face during aconversation, wastes energy and can significantly reduce the usefulcharge lifetime if a device that relies on a limited power source suchas a battery power source.

FIG. 1 illustrates generally an example of a proximity sensor 100according to the present subject matter. The proximity sensor 100includes an energy emitter 101, an energy sensor 102, and a controller103 configured to control the energy emitter 101 and receive informationfrom the energy sensor 102. In certain examples, the energy emitter 101can include a light source, such as a light emitting diode (LED), anacoustic emitter, such as an ultrasonic emitter, an electromagneticemitter, such as a radio frequency emitter or an inductive emitter, orone or more other kinds of energy emitters. In certain examples, theenergy sensor 102 can be selected to match the type of energy emittedfrom the energy emitter 101, such as an optical sensor, an acousticsensor, or an electromagnetic sensor. The controller 103 can control andsynchronize the energy emitter 101, energy sensor 102, or other controlcomponents to generate proximity information. In certain applications,the proximity sensor 100 can sense a change in proximity of an objectnear the proximity sensor 100 by comparing sense events. In someapplications, timely and accurately sensing a change-in-proximity canprovide increased performance of a device using a proximity sensor 100.Generally, better change-in-proximity measurements are provided whenproximity is sensed at a higher frequency. Sensing proximity morefrequently, however, uses more energy. For portable electronic devices,the energy source for powering the proximity sensor 100 can be a limitedsource, such as a battery.

In certain examples, the proximity sensor 100 can include an oscillatorto provide a synchronization (sync) signal, for example, a clock signal,to control components of the proximity sensor 100 including thecontroller 103. Control components can use the sync signal to controlemissions from the energy emitter 101 and determine proximity of anobject based on information from the energy sensor 102, includinginformation about energy from the energy emitter 101 reflected back tothe energy sensor 102. In some examples, the oscillator can be anadjustable oscillator 104, such as a voltage-controlled oscillator(VCO). The adjustable oscillator 104 can vary the frequency of the syncsignal in response to received control information, such as a voltagelevel. In an example, the controller 103 can provide informationindicative of a change-in-proximity. The change-in-proximity informationcan be used to increase or decrease the frequency of the sync signalusing the adjustable oscillator 104. In an example, when thechange-in-proximity information indicates that an object is not presentor is stationary relative to the proximity sensor 100, the oscillatorfrequency can be reduced to save consumption of energy by reducing thefrequency of sensing proximity. When the change-in-proximity informationindicates that an object has entered the sensing range of the proximitysensor 100 or that a sensed object is moving, the frequency of theoscillator 104 can be increased to provide more accuratechange-in-proximity information.

In an example, the proximity sensor 100 can include a communicationmodule 105. In an example, the proximity sensor 100 can be part of anintegrated circuit and can include the communication module 105 forcommunicating over a bus 117, such as an inter-integrated circuit (I²C)communication bus.

In an example, the controller 103 can provide proximity information toother device components. For example, the controller 103 can communicateproximity information using the communication module 105. In an example,the controller 103 can provide an interrupt 106 to other devicecomponents when proximity information is available, or when theproximity information meets or exceeds predefined criteria.

FIG. 2 illustrates generally an example of a proximity sensor 200. Theproximity sensor 200 can include an LED 201, an LED driver 207, a photodiode 202 sensitive to the light emitted by the LED 201, and acontroller 203. The LED driver 207 can be configured to power the LED201 “on” or “off” responsive to command information from the controller203. The LED 201 can be configured to emit light when powered on by theLED driver 207. The photo diode 202 can be configured to receive lightfrom the LED 201 reflected by an object proximate the LED 201 or thephoto diode 202. The photo diode 202 can process the received light toprovide sense information to the controller 203. The controller 203 canbe configured to coordinate the operation of the LED 201 and to processsense information received from the photo diode 202 to provide, forexample, to other components of a device using the proximity sensor 200,proximity information relative to the presence or absence of an objectnear the proximity sensor 200. In certain examples, the controller 203can include a processor 208, such as a digital signal processor (DSP),to process the received sensor information and provide the proximityinformation, including change-in-proximity information, to othercomponents of a device using the proximity sensor 200. In an example,the controller 203 can include an amplifier 209 coupled to the photodiode 202 to amplify information received from the photo diode 202, suchas information in the form of a signal indicative of light received atthe photo diode 202, including information relative to lightcorresponding to light emitted from the LED 201. In an example, aprocessing path of the proximity information can include ananalog-to-digital converter (ADC) 210 to convert analog senseinformation received from the photo diode 202 to digital senseinformation. The controller 203 can include registers 212 to storeprocessing information. In an example, the registers 212 can storehistoric proximity information to use for future processing. Forexample, change-in-proximity information can be provided by processinginformation from one or more past sense events. In an example,change-in-proximity information can use an average of the five mostrecent sense events. It is understood that more or less than five pastsense events can be used to provide change-in-proximity informationwithout departing from the scope of the current subject matter. In anexample, the number of past sense events the sensor processes todetermine change-in-proximity information can depend on the frequency ofsensing proximity information. In an example a weighted average of pastsense event information can be used to provide change-in-proximityinformation. In other examples, other sense events besides the mostrecent sense events can be used.

The controller 203 can include a state machine 213 to synchronize thecontrol of the LED 201 and the sensing and processing of the senseinformation from the photo diode 202. In an example, the state machine213 can reduce the processing burden of the processor 208 by controllingthe sequencing of the LED 201, sampling of sensed information, and thetransfer of the sensed information to the processor 208. In such anexample, the processor 208 can utilize a low-power idle state until thestate machine 213 makes the sense information available to the processor208. Such an example can save energy by reducing the processing load ofthe processor 208.

In an example, the controller 203 can include an adjustable oscillator204 to provide a sync signal to the state machine 213. The frequency ofthe adjustable oscillator 204 can be set based on change-in-proximityinformation received from the processor 208 of the controller 203. In anexample, the frequency can be set using an analog signal and thecontroller can include a digital to analog converter (DAC) 220 toconvert the change-in-proximity information from a digital format to ananalog signal. For example, the adjustable oscillator 204 can include avoltage controlled oscillator (VCO) configured to output a pulse trainat a frequency responsive to a received voltage level.

The adjustable oscillator 204, such as a VCO, can be configured to allowthe proximity sensor 200 to conserve energy. For example, if an objectis not detected by the proximity sensor 200 for an interval of time, ora sensed object has not changed in proximity relative to the proximitysensor 200 for an interval of time, the adjustable oscillator 204 canreduce the synchronization signal frequency. A reduction insynchronization signal frequency can reduce the frequency with which thestate machine 213 triggers a sensing event, including reducing thefrequency at which the LED 201 is turned “on”. Cycling the LED 201 lessoften, which can operate at between 12.5 milliamps and 100 milliamps,can conserve a substantial amount of energy. The frequency of theadjustable oscillator 204 can increase to provide additional proximityinformation, as well as more timely change-in-proximity information,when the proximity sensor 200 first detects proximity to an object, ordetects a sensed object moving.

In certain examples, the proximity sensor 200 can include an ambientlight sensor 214, such as a photo diode sensitive to ambient visiblelight, to provide ambient light information. In an example, thecontroller can include a separate amplifier 218 to amplify the sensedambient light information provided by the ambient light sensor 214. Incertain examples, the controller 203 can include a separate ADC 219 toconvert analog sense information received from the ambient light sensor214 to digital sense information. In certain examples, the proximityphoto diode 202 and the ambient light diode 214 can be integrated witheach other. In an example, the controller 203 can include a multiplexer216, responsive to the state machine 213. The multiplexer 216 canprovide the appropriate sensed information to the processor 208, suchthat the processor 208 can provide either proximity information orambient light information. In an example, the controller 203 can includean accumulator configured to operate with the multiplexer to coordinaterouting sensed information to appropriate locations within the registers212.

In an example, a proximity sensor 200 can include a communication module205. In an example, an integrated circuit can include the proximitysensor 200 and can include a communication module 205 for communicatingover a bus 217, such as an inter-integrated circuit (I²C) communicationbus, to other components of a device using the proximity sensor 200. Itis understood that the proximity sensor 200 can include othercommunication modules supporting other communication protocols withoutdeparting from the scope of the present subject matter. In an example,the controller 203 can provide an interrupt 206 to other devicecomponents when proximity information is available, or when theproximity information meets or exceeds predefined criteria.

FIG. 3 illustrates generally a number of adaptive response timeacceleration curves that can be used to control a proximity sensor. Thegraph illustrates sensory cycle time, milliseconds, illustrated on they-axis, as a function of change-in-proximity measured in distance,millimeters, illustrated on the x-axis. In certain examples, in asensory cycle, a pulse of energy can be emitted from an emitter,reflected energy can be received at a sensor, the reflected energy canbe digitized into proximity information, the digitized proximityinformation can be processed, the processed proximity information can becompared to one or more threshold values, an interrupt can be issuedbased on the comparison, and a communication module, such as an I2Ccommunication module, can be serviced. In some examples, the frequencyof an oscillator controlling the cycle time of the sensory cycle can beadjusted. As the sensory cycle time increases, the frequency ofproximity sensing can decrease or become slower. As the sensory cycletime decreases, the frequency of proximity sensing can increase orbecome faster.

In some examples, a change in proximity information can be detectedusing several prior change-in-proximity measurements and may representan accumulation of the prior measurements, an average of the priormeasurements, or some other measurement algorithm. In an example, anadjustable oscillator, such as the adjustable oscillator 204 of FIG. 2,can be configured to operate at a fixed rate independent of the changein proximity of a sensed object, such as shown by the first curve 301.In an example, the adjustable oscillator can change frequency accordingto a linear function of change-in-proximity information as shown by thesecond curve 302. In an example, the adjustable oscillator can changefrequency according to a non-linear function of change-in-proximityinformation as shown by the third curve 303.

In some examples, ambient light information received from an ambientlight sensor can be processed in a sensory cycle, the processed ambientlight information can be compared to one or more thresholds, and aninterrupt based on the ambient light comparison can be issued. In someexamples, the frequency of an oscillator controlling the cycle time ofthe sensory cycle can be adjusted in response to changes in ambientlight. For example, if a level of ambient light has not substantiallychanged over a predetermined time, the cycle time can be increased toreduce the energy consumed by processing the ambient light samples at aslower frequency. On the other hand, if a substantial change in ambientlight levels is sensed, the sensory cycle time can be reduced to sensethe ambient light level more often such that conditions that depend onor are affected by ambient light, such as display backlighting, can beadjusted in a timely manner with the changing ambient light conditions.

FIG. 4 illustrates generally an example of a method 400 for efficientlyproviding timely and accurate proximity information. At 401, parameterscan be initialized. At 402, a communication module, such as a serialchip-to-chip communication module, can be configured. At 403, a pulse ofenergy can be emitted from an energy emitter, such as a light source. At404, reflected energy information received at a sensor can be digitizedinto proximity information. At 405, the digitized proximity informationcan be processed to determine actual proximity of an object to anapparatus or to determine a change in proximity of an object to anapparatus or a combination thereof.

At 406, change in proximity information can be used to evaluate whetherto change a sensory cycle time. In an example, if thechange-in-proximity information indicates that an object is moving nearthe apparatus of interest, the cycle time can be reduced to sense theproximity of the object faster, in turn, providing more accurate andtimely information about the movement of the object. In an example, ifthe change-in-proximity information indicates an object is not presentor has not moved very much during a interval of time with respect theapparatus of interest, the cycle time can be increased to save energywhile still providing accurate and robust proximity information of thepresence of any objects, or the proximity of a nearly stationary object,with respect to the apparatus of interest. In certain example, variousthresholds can be used to determine when the cycle time can be increasedor decreased. Such thresholds can be programmable, for example, usingregisters of the communication module. At 407, a frequency parameter canbe adjusted. In an example, a value of an output register can be updatedwhen the frequency register is updated. The output register can becoupled to a digital-to-analog converter (ADC) and an analog signal canset the frequency of an oscillator that controls the sequencing of thesensory cycle, and in turn, control the sensory cycle time.

At 408, the change in proximity information can be used to evaluatewhether interrupt should be issued. At 409, an interrupt can be issued.After, at 408, whether an interrupt should be issued is evaluated, or,at 409, the interrupt is issued, a sensory cycle 410, including steps403-409, can repeat. In an example, an interrupt can be used to alertother processes of proximity information, for example, using thecommunication module, or to take further action in response to theproximity information. Various thresholds can be used to determine if aninterrupt should be issued. In an example, such thresholds can saveenergy by triggering other devices to read the proximity informationonly when a significant change in the proximity information is realizedand not after each sensory cycle.

It is understood that other sensory cycles, either alone or incombination, are possible without departing from the scope of thepresent subject matter. For example, but not by way of limitation,proximity sensing and ambient light sensing can be combined in a sensorycycle and the sensory cycle time can be adjusted to accurately andtimely sense proximity and ambient light conditions where suchconditions are in flux, or can be adjusted to save energy consumptionwhere those conditions are substantially unchanging.

Additional Notes

In Example 1, an apparatus can include a light source configured to emita first pulse of light, a sensor configured to receive reflected lightfrom the first pulse of light, a control circuit including a processor,the processor configured to provide first proximity information of theapparatus with respect to an object using the reflected light, whereinthe control circuit is configured to control the light source, tocompare the first proximity information with second proximityinformation, and to modulate a delay between the first pulse of lightand a subsequent pulse of light using the comparison.

In Example 2, the second proximity information of Example 1 isoptionally associated with a second pulse of light.

In Example 3, the control circuit of any one or more of Examples 1 or 2is optionally configured to decrease the delay when the comparisonindicates that the proximity of the apparatus to the object has changedby a first threshold distance.

In Example 4, the control circuit of any one or more of Examples 1-3 isoptionally configured to increase the delay when the comparisonindicates that the proximity of the apparatus to the object has notchanged by a threshold distance.

In Example 5, the processor of any one or more of Examples 1-4 isoptionally configured to provide an indication of a change in theproximity of the apparatus to the object.

In Example 6, the control circuit of any one or more of Examples 1-5optionally includes an adjustable oscillator to control the delay.

In Example 7, the oscillator of any one or more of Examples 1-6optionally includes a voltage-controlled oscillator.

In Example 8, the processor of any one or more of Examples 1-7 isoptionally configured to provide a digital indication of thechange-in-proximity of the apparatus to the object, and the controlcircuit of any one or more of Examples 1-7 optionally includes adigital-to-analog converter configured to receive the digital indicationof the change-in-proximity, and to provide an analog voltagerepresentation of the change-in-proximity to the voltage-controlledoscillator.

In Example 9, the light source of any one or more of Examples 1-8optionally includes an infrared diode.

In Example 10, the second proximity information of any one or more ofExamples 1-9 optionally includes a plurality of previous comparisons ofproximity information.

In Example 11, A method can include emitting a first pulse of light froma light source, receiving reflected light from the first pulse of light,providing first proximity information of the apparatus with respect toan object using the reflected light, comparing the first proximityinformation with second proximity information, and modulating a delaybetween the first pulse of light and a subsequent pulse of light usingthe comparison.

In Example 12, the method of of any one or more of Examples 1-11optionally includes receiving second reflected light from a second pulseof light, and providing the second proximity information of theapparatus with respect to the object using the second reflected light.

In Example 13, the modulating of any one or more of Examples 1-12optionally includes decreasing the delay when the comparison indicatesthat the proximity of the apparatus to the object has changed by atleast a first threshold distance.

In Example 14, the modulating optionally includes increasing the delaywhen the comparison indicates that the proximity of the apparatus to theobject has not changed by more than a first threshold distance.

In Example 15, the providing the first proximity information of any oneor more of Examples 1-14 optionally includes providing an indication ofa change-in-proximity of the apparatus to the object.

In Example 16, the modulating the delay of any one or more of Examples1-5 optionally includes modulating an oscillator frequency to controlthe delay using the indication of the change-in-proximity.

In Example 17, the providing the indication of the change-in-proximityof any one or more of Examples 1-16 optionally includes providing adigital representation of the change-in-proximity of the apparatus tothe object.

In Example 18, the modulating the oscillator frequency of any one ormore of Examples 1-17 optionally includes using the digitalrepresentation of the change-in-proximity of the apparatus to theobject.

In Example 19, the modulating the oscillator frequency of any one ormore of Examples 1-18 optionally includes converting the digitalrepresentation of the change-in-proximity of the apparatus to the objectto an analog voltage signal, receiving the analog voltage at avoltage-controlled oscillator, and modulating an oscillator frequency ofthe voltage controlled oscillator using the analog voltage.

In Example 20, the comparing the first proximity information with secondproximity information of any one or more of Examples 1-19 optionallyincludes comparing the first proximity information with a plurality ofprevious comparisons of proximity information.

Example 21 can include, or can optionally be combined with any portionor combination of any portions of any one or more of Examples 1-20 toinclude, subject matter that can include means for performing any one ormore of the functions of Examples 1-20, or a machine-readable mediumincluding instructions that, when performed by a machine, cause themachine to perform any one or more of the functions of Examples 1-20.These non-limiting examples can be combined in any permutation orcombination.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

All publications, patents, and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim. Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, in an example, the code can be tangiblystored on one or more volatile, non-transitory, or non-volatile tangiblecomputer-readable media, such as during execution or at other times.Examples of these tangible computer-readable media can include, but arenot limited to, hard disks, removable magnetic disks, removable opticaldisks (e.g., compact disks and digital video disks), magnetic cassettes,memory cards or sticks, random access memories (RAMs), read onlymemories (ROMs), and the like.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

1. An apparatus comprising: a light source configured to emit a firstpulse of light; a sensor configured to receive reflected light from thefirst pulse of light; a control circuit including a processor, theprocessor configured to provide first proximity information of theapparatus with respect to an object using the reflected light; andwherein the control circuit is configured to control the light source,to compare the first proximity information with second proximityinformation, and to modulate a delay between the first pulse of lightand a subsequent pulse of light using the comparison.
 2. The apparatusof claim 1, wherein the second proximity information is associated witha second pulse of light.
 3. The apparatus of claim 1, wherein thecontrol circuit is configured to decrease the delay when the comparisonindicates that the proximity of the apparatus to the object has changedby a first threshold distance.
 4. The apparatus of claim 1, wherein thecontrol circuit is configured to increase the delay when the comparisonindicates that the proximity of the apparatus to the object has notchanged by a threshold distance.
 5. The apparatus of claim 1, whereinthe processor is configured to provide an indication of a change in theproximity of the apparatus to the object.
 6. The apparatus of claim 5,wherein the control circuit includes an adjustable oscillator to controlthe delay.
 7. The apparatus of claim 6, wherein the oscillator includesa voltage-controlled oscillator.
 8. The apparatus of claim 7, whereinthe processor is configured to provide a digital indication of thechange-in-proximity of the apparatus to the object; and wherein thecontrol circuit includes a digital-to-analog converter configured toreceive the digital indication of the change-in-proximity, and toprovide an analog voltage representation of the change-in-proximity tothe voltage-controlled oscillator.
 9. The apparatus of claim 1, whereinthe light source includes an infrared diode.
 10. The apparatus of claim1, wherein the second proximity information includes a plurality ofprevious comparisons of proximity information.
 11. A method comprising:emitting a first pulse of light from a light source; receiving reflectedlight from the first pulse of light; providing first proximityinformation of the apparatus with respect to an object using thereflected light; comparing the first proximity information with secondproximity information; and modulating a delay between the first pulse oflight and a subsequent pulse of light using the comparison.
 12. Themethod of claim 11, including: receiving second reflected light from asecond pulse of light; and providing the second proximity information ofthe apparatus with respect to the object using the second reflectedlight.
 13. The method of claim 11, wherein the modulating includesdecreasing the delay when the comparison indicates that the proximity ofthe apparatus to the object has changed by at least a first thresholddistance.
 14. The method of claim 11, wherein the modulating includesincreasing the delay when the comparison indicates that the proximity ofthe apparatus to the object has not changed by more than a firstthreshold distance.
 15. The method of claim 11, wherein the providingthe first proximity information includes providing an indication of achange-in-proximity of the apparatus to the object.
 16. The method ofclaim 15, wherein the modulating the delay includes modulating anoscillator frequency to control the delay using the indication of thechange-in-proximity.
 17. The method of claim 16, wherein the providingthe indication of the change-in-proximity includes providing a digitalrepresentation of the change-in-proximity of the apparatus to theobject.
 18. The method of claim 17, wherein the modulating theoscillator frequency includes using the digital representation of thechange-in-proximity of the apparatus to the object.
 19. The method ofclaim 18, wherein the modulating the oscillator frequency includes:converting the digital representation of the change-in-proximity of theapparatus to the object to an analog voltage signal; receiving theanalog voltage at a voltage-controlled oscillator; and modulating anoscillator frequency of the voltage controlled oscillator using theanalog voltage.
 20. The method of claim 11, wherein the comparing thefirst proximity information with second proximity information includescomparing the first proximity information with a plurality of previouscomparisons of proximity information.